#include <fxos/util.h>
#include <cstdlib>
#include <cstring>

#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>

/* Empty buffer initialized with given byte */
Buffer::Buffer(size_t size, int fill)
{
	m_data = malloc(size);
	if(!m_data) throw std::bad_alloc();

	m_size = size;
	memset(m_data, fill, size);

	m_path = "(anonymous)";
}

/* Buffer initialized from file */
Buffer::Buffer(std::string filepath, ssize_t size, int fill)
{
	char const *path = filepath.c_str();

	int fd = open(path, O_RDONLY);
	if(!fd) throw std::runtime_error(format("cannot open '%s'", path));

	struct stat statbuf;
	ssize_t x = fstat(fd, &statbuf);

	if(x < 0)
	{
		close(fd);
		throw std::runtime_error(format("cannot stat '%s'", path));
	}

	m_size = (size < 0) ? statbuf.st_size : size;
	size_t size_to_read = std::min(m_size, (size_t)statbuf.st_size);

	m_data = malloc(m_size);
	if(!m_data) throw std::bad_alloc();

	/* Read buffer and fill whatever is left */
	memset(m_data, fill, m_size);
	x = read(fd, m_data, size_to_read);

	close(fd);
	if(x != (ssize_t)size_to_read)
	{
		throw std::runtime_error(format(
			"error while reading '%s'", path));
	}

	m_path = filepath;
}

/* Create a buffer by copying another buffer */
Buffer::Buffer(Buffer const &other):
	Buffer(other.size(), 0x00)
{
}

/* Create a buffer by copying and resizing another buffer */
Buffer::Buffer(Buffer const &other, size_t new_size, int fill):
	Buffer(new_size, fill)
{
	memcpy(m_data, other.data(), std::min(new_size, other.size()));
}

/* Free allocated data, obviously */
Buffer::~Buffer()
{
	free(m_data);
}

/* Buffer size */
size_t Buffer::size() const noexcept
{
	return m_size;
}

/* Buffer data */
char *Buffer::data() noexcept
{
	return static_cast<char *>(m_data);
}
char const *Buffer::data() const noexcept
{
	return static_cast<char const *>(m_data);
}

/* File path */
std::string Buffer::path() const noexcept
{
	return m_path;
}